1. Field of the Invention
The invention relates to an electric vacuum switch with two cup-shaped switching contact components which are composed of electrically conductive material and each consisting of a contact carrier having a base and having a cylinder jacket-shaped wall. A contact ring having a ring-shaped contact surface is placed onto the wall at the end side facing away from the base. The wall is divided into segments by radial slots running obliquely to the contact component axis.
2. Description of the Prior Art
An electric vacuum switch of this type is known and described, for example, in German Pat. No. 1 196 751, in which a switching tube for high contact ratings is disclosed which, in particular, must exhibit a high short-circuiting disconnect capability. In order to effect the disconnection, the contact surfaces, arranged one above another, of the two cup-shaped contact components are mechanically separated from one another, thus producing an arc consisting of ionized metal vapor. In order to prevent the destruction of the contact surfaces, the arc is to move rapidly across the contact surfaces. For this purpose, by bending the current path, a resultant magnetic field is produced at right angles to the current direction and deflects the arc current in a third, perpendicular direction and causes it to rotate. This is achieved by means of oblique slotting of the contact components. The contact carriers are thus at least partially divided into individual segments.
When high currents are disconnected, the contact components are also subject to mechanical load. In order to provide the contact components with a greater stability, the German Pat. No. 1 196 751 proposes that the slotting of the contact components should not extend to the contact surfaces. This produces continuous contact rings. This also has the advantage that the rotation of the arc is not disturbed by breaks in the contact surfaces, and that there is relatively no heavy erosion of the contact material in the region of the slots.
For the same purpose it is known from German AS No. 17 65 263 to surround the obliquely slotted contact components with a casing body consisting of high-grade contact material at least on the contact surfaces and the laterally adjoining surfaces of the contact components. The mechanical stability and the arc rotation are provided by the slotted core of the contact components. The favorable erosion characteristic is insured by the continuous casing body which can be relatively thin and thus permits an economical use of high-grade contact material.
Suitable contact materials are those which have been purified in a zone melting process. It is necessary to use materials of this type to insure that during the disconnection process, gases are released from the contact material in addition to the metal which has been vaporized by the arc. Gases of this kind would impair the high vacuum and promote a re-ignition of the arc.